The present invention relates to swirl-chamber Diesel engines.
A swirl-chamber Diesel engine is one in which, during compression stroke of a reciprocating piston, charged air in a main combustion chamber arranged in a cylinder is compressed so that part thereof is forced into a swirl chamber through a communicating passage, generating swirl therein; fuel is injected into the swirling air in the swirl chamber and ignited by the heat within the swirl chamber; and the combustion product resulting from the combustion in the swirl chamber, which includes burning flame and fuel droplets, enters into the main combustion chamber through the communicating passage, evaporating the fuel droplets to facilitate a so-called diffusion burning. A known swirl-chamber Diesel engine includes a cylinder block, a piston reciprocally movable in a cylinder formed in the cylinder block, and a cylinder head secured to the cylinder block to close the cylinder so that a main combustion chamber is formed in the cylinder between the crown of the piston and the cylinder head. The cylinder head has formed therein a swirl chamber communicating with the main combustion chamber through a communicating passage also formed through the cylinder head. The passage is so shaped and inclined as to permit, during the compression stroke of the piston, part of the charged air in the main combustion chamber to enter into the swirl chamber along a line tangent to the swirl chamber wall thereby to generate swirl in the swirl chamber. A fuel injection nozzle is mounted to the cylinder head with its spout or spray tip communicating with the swirl chamber. The fuel injection nozzle points to the swirl chamber wall disposed adjacent to a shoulder section defining part of the swirl chamber wall and is inclined such that a jet of fuel injected may be directed along the swirl within the swirl chamber and may not enter directly into the main combustion chamber through the communicating passage. A heater plug or glow plug extends into the swirl chamber to produce heat close to the jet of fuel injected to give a starting air. In order to evenly diffuse the fuel droplets and combustion products or flame entering into the main combustion chamber from the swirl chamber through the spout passage, the piston is formed at its crown with a depression consisting of cup-shaped cavities communicating at their junctions with the swirl chamber.
In a swirl-chamber Diesel engine, in order to facilitate evaporation of the fuel droplets entering into a main combustion chamber through a communicating passage and to prevent carbonization of the fuel droplets owing to their thermal decomposition with insufficient oxygen, it is desired to design the combustion chamber so that sufficient oxygen may be present around every fuel droplets. This is one of the effective measures to reduce emissions of smoke.